In 1942, with World War II in full swing, a young military scientist learned of the Allies’ plans to invade northwestern Africa by sea to dislodge the nearby Axis forces.

The scientist, Walter Munk, who was in his mid-20s, hastily did some research and found that waves in the region were often too high for the boats carrying troops to reach the beaches safely.
Disaster could loom.
He mentioned it to his commanding officer, but was brushed off.
“ ‘They must have thought about that,’ ” Dr. Munk, now 97, recalled being told.
But the young scientist persisted, calling in his mentor at the Scripps Institution of Oceanography near San Diego to help.

They devised a way to calculate the waves the boats could expect to face.
Their work helped the boats land in a window of relative calm, and the science of wave prediction took off, becoming part of the planning for the D-Day landings in 1944.

Such feats explain why Dr. Munk is sometimes called the “Einstein of the oceans.”
Longtime colleagues describe him as a courtly man of boundless curiosity, with an uncanny ability to search out important problems at just the right time.
In addition to wartime wave forecasting, Dr. Munk has done pioneering research in ocean sound transmission, deep-sea tides and even climate change, though some of his work in the field has been controversial.

Even today, well into his eighth decade of scientific work, his desk holds books and papers thick with geophysics formulas, and he continues to tackle projects ranging from using underwater sound signals to measure warming ocean temperatures to how winds cause the Gulf Stream.
Had he more time, Dr. Munk said, he would work on geoengineering.
“He has a real knack for picking problems that are ripe to really get new fields started,” said Peter Worcester, a research oceanographer at Scripps who has worked with Dr. Munk on a number of issues, including climate change.

Photos and video clips spanning the career of Scripps oceanographer Walter Munk.

Video courtesy of UC San Diego Creative Services and Publications.

Certain images used courtesy of Ansel Adams.

Born in 1917 to a banking family of Jewish heritage, Dr. Munk grew up in Vienna, with frequent trips to the Austrian countryside.
His father served occasionally as a chauffeur to Franz Joseph, the Austrian emperor, during World War I. “He had the only Rolls-Royce in Vienna,” Dr. Munk recalled.
His parents later divorced, and he was closer to his mother, who sent him to a school in upstate New York in 1932.
After taking night classes at Columbia University, he decided to leave the family business of banking and gained admission to the California Institute of Technology, where he studied applied physics. While spending the summer of 1939 near a girlfriend in the oceanside town of La Jolla, outside San Diego, he landed a job with Scripps (now part of the University of California, San Diego), where he has worked most of his career.

Colleagues say Dr. Munk took advantage of emerging computer analysis tools to help turn his direct observations of the ocean into sophisticated research projects.
But Dr. Munk says he is concerned that today’s young oceanographers rely too much on computers, and fail to ask fundamental questions or take enough risks.
“Computers are a lot cheaper than boats, and a lot more comfortable,” he said.
“And I’m a little worried about so many people doing computer experiments and losing their ability, the American leadership, in measurements at sea.”

His seafaring work includes some notable moments in world history.
Days before nuclear tests were performed at Bikini Atoll in 1946, Dr. Munk and a colleague dropped dye in the water to assess how quickly radioactive materials would flush out of the lagoon.
Near the test site of the far more powerful hydrogen bomb on Eniwetok Atoll in 1952, he monitored the ocean for a potential tsunami.
It didn’t happen, though Dr. Munk and his crew were doused by radioactive rain and had to toss their clothes overboard.

The high point of his career, as Dr. Munk calls it, came in 1991, when he traveled to Heard Island, a remote spot in the Southern Indian Ocean, to test long-range sound signals in the ocean.
Dr. Munk had worked extensively with colleagues on ocean acoustics, a useful field for detecting or concealing submarines.
The goal of the Heard Island experiment was to determine whether a sound generated from the South Indian Ocean could be heard in other corners of the world.
The speed at which the sound signals traveled could provide useful data on warming ocean temperatures, Dr. Munk reasoned, because the sound would travel slightly faster as the ocean warmed.

Hours before the experiment was to begin, Dr. Munk was awakened by a call from Bermuda.
From thousands of miles away, the listening post had already heard the sound before the experiment had begun.
As it turned out, the Bermuda post had heard the brief sound check that technicians had made while preparing for the full test.
“And that was the best news that I’ve ever heard,” Dr. Munk recalled.
The Heard Island broadcasts became known as the “sound heard around the world.”

But Dr. Munk’s zeal for using ocean sounds to measure climate change created trouble a few years later.
In 1994, as part of a Scripps project, he sought to install a sound transmitter in the Monterey Bay National Marine Sanctuary off the coast of California to help measure ocean temperatures changing over time. (Another one was installed off Hawaii.)
But environmentalists feared that the broadcasts would hurt whales, which navigate and find food by means of their own sonar, and feed in the sanctuary.
The Natural Resources Defense Council asked for and received a public hearing in an effort to halt the Monterey Bay project.
“What happened here was a head-on collision between Walter Munk and whales. And that was the perception,” recalled Joel Reynolds, a senior lawyer for the defense council.
Dr. Munk and the military, which was largely funding the study, did not anticipate the level of public concern that the acoustics project would generate, he said.
After negotiations with the environmentalists, Dr. Munk and Scripps agreed to move the listening post farther off the California coast and prioritize a study of the sounds’ effects on marine mammals.

The clash over ocean acoustics, recounted in Joshua Horwitz’s 2014 book “War of the Whales,” illustrated a “chasm” between physical oceanographers and marine biologists, said Mr. Reynolds, who praised Dr. Munk as “one of the extraordinary oceanographers in history.”

Dr. Munk still yearns to use sound to measure the warming ocean.
“I am convinced that you can do good underwater acoustics without hurting the whales, with some sensible precautions,” he said.
For example, during Naval exercises, scientists must make sure there are no pods of whales nearby, and only gradually increase the sound.
He understood the concerns about whales, he said, and all sides “have to want to work together.”

His long career has also given Dr. Munk perspective on his earliest work on waves.
After their success in North Africa, he and his colleagues at Scripps opened a wave-prediction school for military officers, and some of the graduates went on to help forecast waves off Normandy ahead of the 1944 D-Day landings.

The curriculum changed constantly, Dr. Munk recalled, as the scientists learned more about the science of waves on the fly, essentially inventing the field.
“When we then look backwards, the fact that the landings took place during good weather was mostly luck, to some small extent skill,” Dr. Munk said of North Africa.

Nowadays, as he forges ahead on wind, waves and other projects, he occasionally forgets the times of meetings and gets around with the aid of a walker.
But he remains a frequent presence in Scripps, walking the halls of a building that now bears his name.
The secret to his longevity?
“I like my work and I like my life, and I enjoy doing it,” he said.